Process for condensation of hydrocarbons by contact with concentrated sulfuric acid in silica gel



Patented Jan. 20, 1948 PROCESS FOR CONDENSATION OF HYDRO- CARBONS BYCONTACT WITH CONCEN- TRATED SULFURIC ACID IN SILICA GEL Frank G.Ciapetta. Drexel Hill, Pa., asslgnorto The Atlantic Refining Company.Philadelphia, Pa., a corporation of Pennsylvania No Drawing. Or'glnalapplication July 9, 1942.

Divided and this application May 27, 1944, Serial No. 537,734

7 Claims. (Cl. 260-671) Serial No. 450,338.

The present invention relates to an improved catalyst composition andits use in catalyzi r actions between organic compounds. Moreparticularly this invention relates to an improved sulfuric acidcatalyst and its use in catalyzing reactions between organic compoundswhich are susceptible of reaction in the presence of concentratedsulfuric acid.

This application is a division of my co-pending application, Serial No.450,338. filed July 9, 1942, now U. 8. Patent 2,430,803, dated November11, 1947.

In accordance with this invention, there is provided a dry, granularcatalyst comprising silica gel impregnated with sulfur trioxide in anamount sufficient only to unite with the water content of the gel toform concentrated sulfuric acid, i. e., substantially 100 per centH2804. in the pores of the gel. Such acid is very tightly held withinthe pores of the gel by adsorption, absorption, or the formation of acomplex compound between the acid and the gel, such compound being ofunknown composition.

The improved silica gel-sulfuric acid catalyst of this invention isadapted for use in catalyzing a variety of chemical reactions, andparticularly the polymerization of oleiinic compounds, the alkylation ofisoparaflins with olefins, the alkylation of aromatic hydrocarbons,naphthenic hydrocarbons or phenolic compounds with olefins or alcohols,the dehydration of alcohols to form ethers or oleflns, and the hydrationof olefins with water to form alcohols. These reactions are typicalexamples in which the catalyst of the present invention may beadvantageously employed, and are not to be construed as limitin thescope of the invention.

In the preparation of the catalyst, a granular silica gel having a watercontent within the range of 3 per cent to 15 per cent by weight isplaced in a suitable vessel and a stream of vaporous S: is passed intoand through the silica gel. The silica gel may be of any desired meshsize, for example, 4-8, -30, -80, -60, or fine mesh such as 100-300. The80: may be produced by heating fuming sulfuric acid to a temperaturesufllciently high to drive oil the S0: as vapors, or

be cooled and is then ready for use. Depending upon the initial watercontent of the gel, 1. e.. 3 per cent to 15 per cent by weight, thecatalyst may contain from 15.0 per cent to 46 per cent by weight ofconcentrated H2804. The catalyst is a dry, ranular material which isreadily handled and which can be stored without dimculty forconsiderable periods, provided that precautions are taken to preventcontact with moisture.

The catalyst may be used in promoting reaction between organic compoundseither in the liquid phase or in the vapor phase, depending upon thereactivity of the compounds and the composition of the products which itis desired to produce. The dry silica gel-H2804 catalyst possesses anumber of advantages over 'the conventional liquid H2804 catalysts.including ease of handling, a relatively higher catalytic efficiency dueto increased contact surface, and the fact that the chemical reactionscan be effected simply by passing the reactants in the liquid or vaporphase thereof.

. A silica gel-H2804 catalyst was prepared by heating 30 per cent fumingsulfuric acid and passing the resulting vaporous 803 through a bed ofcommercial 4-8 mesh silica gel containing 5.7 per cent by weight ofwater. The passage of the S0: was continued until S0: vapors were nolonger absorbed, thus indicating that the gel was thoroughly impregnatedor saturated with $03. The reaction of the S0: with the water content ofthe gel caused a considerable rise in temperature of the gel. The gelwas then brought to a temperature of about 212 F. and a stream of drynitrogen was passed throughthe gel at this temperature in order to flushout any excess The dry gel containing the firmly held concentrated H3804was then cooled, and the gel was found to contain about 23.0 per cent byweight of concentrated H2804 (100 per cent). The gel, as above prepared,was employed as a catalyst in the following reactions.

1. Isobutylene was passed through volumes of the silica gel-H2804catalyst at a rate of 235 volumes of isobutylene per minute, fora'period handling) of 6.2 hours at a temperature of 70 1". and atatmospheric pressure. There was obtained 253 volumes of liquidhydrocarbon product (isobutylene polymers) having an A. P. I. gravity of56.6, representing a weight per cent yield of 94.0 based upon theisobutylene charged, An assay distillation of the liquid product gave0.8 volume per cent up to 203 F., 20.5 volume per cent between 204 F.and 302 F. (di-isobutylene fraction), 58.7 volume per cent between 303F. and 365 F. (tri-isobutylene fraction) 16.4 volume per cent bottoms(higher polymers and tar), and 3.6 volumes per cent loss (decompositionand bandling) v 2. Isobutylene, in the liquid phase, was passed through80 volumes of the silica gel-H2804 catalyst at a rate of 1 volume ofliquid isobutylene per minute, for a period of 5 hours at a temperatureof 67 F., and at a superatmospheric pressure of 30 pounds per squareinch. There was obtained 305 volumes of liquid hydrocarbon product(isobutylene polymers) having an A. P. I. gravity of 60.8, representinga weight per cent yield of 97.8 based upon the isobutylene charged. Anassay distillation of the liquid product gave 1.0 volume per cent up to203 F.. 35.6 volume per cent between 204 F. and 302 F. (di-isobutylenefraction), 46.0 volume per cent between 303 F. and 365 F.(tri-isobutylene fraction), 6.8 volume per cent bottoms (higher polymersand tar), and 10.6 volume per cent loss (decomposition and It will benoted that in this run, the pressure employed appeared to cause anincreased production of di-isobutylene, and a decreased production oftri-isobutylene and higher polymers, as compared with the results in thefirst example.

3. A liquefied mixture comprising 266 volumes of isobutane and 117volumes of isobutylene was passed through 60 volumes of silica gel-HzSO4catalyst under a pressure of 50 pounds per squareinch at temperature of80 F., the contact time being 39 minutes. The liquid product recoveredfrom the reaction amounted to 90 volumes at atmospheric pressure and hadan A. P. I. gravity of 66.4". An assay distillation of the product gave3.4 volume per cent up to 203 F.,

10.2 volume per cent between 204 F. and 302 F. (iso-octane fraction, A.P. I. gravity 67.8, bromine number 16.9), 48.9 volume per cent between303 F. and 365 F. (tri-isobutylene fraction), 11.4. volume per centbottoms (higher polymers and tar), and 26.1 volume per cent loss(decomposition and handling).

4. A mixture comprising 113 parts by weight of benzene and 43 parts byweight of propylene was passed through 80 volumes of silica gel- H2804catalyst at atmospheric pressure and at a, temperature of 70 F., thereaction time being 2 hours. The liquid product recovered from thereaction amounted to 131 parts by weight and had an A. P. I. gravity of31.1. An assay distillation of the product gave 475 volume per cent upto 212 F. (mostly benzene), 25.0 volume per cent between 213 F. and 320F. (mono-isopropyl benzene fraction), 25.0 volume per cent bottoms(di-isopropyl benzene fraction), and 2.5 volume percent loss(decomposition and handling).

The above examples are merely illustrative of several types of reactionswhich may be promoted with the silica gel-H2804 catalyst of myinvention. The polymerization of unsaturates -may be carried outattemperatures between 0 F. and 450 F., in the liquid phase or in thevacohols, and the like.

per phase, using pressures of from atmospheric up to about 1000 poundsper square inch. For

'example. isobutylene. per se, may be polymerized,

or mixtures of different olefins such aspropylene and butylene may beco-polymerized. The alkylation of isoparafhns or aromatics with olefinsmay be effected at temperatures between 0 F. and 150 F. at atmosphericor' superatmos pheric pressure.

My catalyst may also be used to promote other reactions, including thealkylation of aromatic hydrocarbons, naphthenic hydrocarbons, andphenolic compounds with olefins or alcohols such as methyl alcohol,ethyl alcohol, the propylalcohols, the butyl alcohols, the amyl al- Oroleiins such as ethylene, propylene or butylene may be hydrated to thecorresponding alcohols in the presence of my silica gel-H2804 catalyst.On the other hand, alcohols such as ethyl alcohol, propyl alcohol, butylalcohol and the like may be dehydrated under the proper conditions inthe presence of my catalyst to give either oleflns or ethers. Forexample, ethyl alcohol may be dehydrated by passage over my catalyst attemperatures of C. to C. to form diethyl ether, or the dehydration maybe effected at temperatures of C. to C. to form ethylene. The formationof esters by the reaction of alcohols with fatty acids, naphthenicacids, and the like may be promoted by the presence of my catalystcomposition. These, and many other reactions which are catalyzed by thepresence of concentrated sulfuric acid, are included within the scope ofmy invention.

In utilizing the silica gel-H2804 catalyst for promoting chemicalreactions, the catalytic efficiency 0f the composition necessarilydecreases with extended use, due to dilution of the sulfuric acid heldfirmly in the pores of the gel and the accumulation of tarry or otherforeign matter upon the surfaces of the gel particles. At such time asthe catalytic efficiency has decreased to an extent which makes furtheruse impractical, the catalyst may be regenerated by washing with water,or solvents, or by'steaming, and then re-impregnating the gel with S03.In this manner the gel may be reused many times, only at the expense ofcleaning and 're-impregnating with S03. In those cases where thecatalyst becomes inefficient primarily as a result of tarryaccumulations, the catalyst may b regenerated simply by washing with asolvent for the tarry material, no reimpregnation with S0: beingnecessary.

I claim:

1. The method of effecting reaction between organic compoundssusceptible of reaction in the presence of a concentrated sulfuric acidcatalyst, which comprises bringing said organic compounds into intimatecontact with silica gel having an initial water content of 3% to 15% byweight impregnated with sulfur trioxide in quantity suflicient to unitwith the water content of said gel to form 100% sulfuric acid in thepores of said gel, and removing from contact with said impregnated gel,the reaction product of said organic compounds.

2. The method of polymerizing unsaturated hydrocarbons to producehydrocarbons of higher molecular weight, which comprises bringing saidunsaturated, hydrocarbons into intimate contact with silica gel havingan initial water content of 3%, to 15% by weight impregnated with sulfurtrioxide in quantity sufiicient to unite with the water content of saidgel to form 100% sulfuric acid in the pores of said gel, and removingfrom contact with said impregnated gel, the resulting hydrocarbonpolymers.

3. The method of alkylating an isoparafiin with an olefin, whichcomprises bringing a mixture of said isoparafiin and said olefin intointimate contact with silica gel having an initial water content of 3%to 15% by weight impregnated with sulfur trioxide in quantity sufilcientto unite with the water content of said gel to form 100% sulfuric acidin the pores of said gel, and removing from contact with saidimpregnated gel, the resulting alkylated isoparamn.

4. The method of alkylating an aromatic hydrocarbon with an olefin,which comprises bringing a mixture of said aromatic hydrocarbon and saidolefin into intimate contact with silica gel having an initial watercontent of 3% to 15% by weight impregnated with sulfur trioxide inquantity suflicient to unite with the water content of said gel to form100% sulfuric acid in the pores of said gel, and removing from contactwith said impregnated gel, the resulting alkylated aromatic hydrocarbon.

5. The method of effecting reaction between organic compoundssusceptible of reaction in the presence of a concentrated sulfuric acidcatalyst, which comprises bringing said organic compounds into intimatecontact with a catalyst prepared by passing sulfur trioxide throughsilica gel having an initial water content of 3% to 15% by weight tounite with the water content of the gel to form concentrated sulfuricacid in the pores of said gel, and removing from said gel any excess ofsulfur trioxide, whereby the acid concentration in the gel issubstantially 100%.

6. The method of effecting reaction between organic compoundssusceptible of reaction in the presence of a concentrated sulfuric acidcatalyst, which comprises bringing said organic compounds into intimatecontact with a catalyst prepared by passing sulfur trioxide throughsilica gel having an initial water content of 3% to 15% by weight tounite with the water content of the gel to form concentrated sulfuricacid in the pores of said gel, heating said gel and passing an inert gasthrough said gel to remove therefrom any excess of sulfur trioxide,whereby the .acid concentration in the gel is substantially 100%.

7. A method of polymerizing isobutylene, which comprises bringingisobutylene into intimate contact, at a temperature of about F., withsilica gel having an initial water content of 3% to 15% by weightimpregnated with sulfur trioxide in quantity sufficient to unite withthe water content of said gel to form sulfuric acid in the pores of saidgel, and removing from contact with said impregnated gel, the resultingisobutylene polymers.

FRANK G. CIAPEITA.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,933,091 Bertsch Oct. 31, 19332,131,196 Schneider Sept. 2'7, 1938 2,181,640 Deanesly et al Nov. 28,1939 2,258,368 Stevens et a1. Oct. 7, 1941 2,293,353 Moravec et a1. Aug.18, 1942 2,384,311 Kearby Sept. 4, 1942

